1. Field of the Invention
The present invention relates to a camera module and a portable terminal provided with the camera module.
2. Description of the Related Art
A camera module having the function of autofocusing (AF) and/or zooming used for a portable terminal such as a mobile telephone is required to be constructed small in size.
When a camera module having an autofocusing (AF) function or zooming function is reduced in size, zoom lenses also must be downsized. However, the zoom lenses must me moved in the direction of the optical axis of the lenses in order to change the focal distance thereof. Therefore, it is necessary to downsize the lenses, to secure as long traveling distance of lenses as possible in a small space, and to downsize lens holders for retaining lenses, moving mechanism or driving mechanism thereof. A variety of devisal are required to downsize the camera module while keeping easiness of assembling and adjusting.
As a prior art concerning a camera module like this, there is disclosed a camera for example in JP 10-628652 (hereafter referred to as patent literature 1). In the literature 1, a driving mechanism of camera is shown which is provided with a motor which serves both for film feeding and autofocusing and a motor for zooming in order to perform the driving for autfocusing and the driving for feeding film in the opposite direction by a single driving motor with a simple construction constructed at a low cost, in which the transmission of the driving force of the motor serving both for film feeding and autofocusing is switched by means of planetary gear type clutches in the state of film winding and film feeding and in the state of film rewinding, and in which a gear for autufocus-driving is located where it can mesh with one or other of the planetary gear drives of the planetary gear type clutches, the position of one of the planetary gear is retained in the state it meshes with the gear for autofocus-driving with the limiting member and the limiting member being driven by the projecting and subtracting action of the zooming system in order to allow the limiting member to retain the driving system in the state autofocus-driving is possible. Further, in JP 7-63970 (hereafter referred to as patent literature 2) is disclosed a camera in which a cylindrical cam located at the side of the optical lens system thereof is driven by a motor to move a lens holder for zooming and a lens holder for focusing.
In Japanese Laid-Open Utility Model Application No. 2-1710 (hereafter referred to as patent literature 3) is disclosed a lens attaching structure in which the lens holder is provided with a reference surface to which an end face of the lens in the optical direction, a concaved portion is provided on the reference surface outer side of the periphery of the lens, and the lens is fixed by filling an adhesive agent in the concaved portion.
Further, as the downsizing of camera module for a portable terminal advances, the driving motor becomes small and the attaching of the motor becomes difficult as mentioned before. To resolve the problem, a composition is known in which a cylindrical step motor is located effectively in an lens-barrel to reduce the thickness of the lens-barrel and the lenses can be driven accurately and at high speed (hereafter referred to prior art 1). According to this prior art, the front lens group is located fixedly in the front side of the aperture position in the lens-barrel, the rear lens group is formed to have its lower part removed, a shutter consisting of two blades which are driven to open and shut in a range not to interfere with the removed portion, the shutter serving both as the aperture, and the cylindrical step motor is located astride of the aperture position in the space below the rear lens group and front lens group.
Further, a composition is known in which, in order to construct a camera module to be thin and furthermore to realize accurate focusing and image zooming by moving lens position, lenses are fixed to the first and second barrel so that the lenses for focusing an image to an image pickup device do not deviate, further the first and second barrel are fixed to the housing, a guide groove is formed on one side of the housing to receive the extended part of the first and second housing so that the first and second housing can be slid (hereafter referred to as prior art 2) In the prior art 2, the rotation of the gear connected to the rotation shaft of the motor is converted to vertical and horizontal motion and the distance between the first barrel and the second barrel is adjusted.
Further, there are known camera modules; one in which the casing of the camera module is formed into a box having one of the side walls opened and at least moving lenses among the zoom lenses can be assembled from the opening (hereafter referred to as prior art 3); one in which a supporting part of the guide of lens frames is provided in a housing retaining an object side lens and lens frames for zooming and focusing are driven by means of two lead screws to utilize the space of lens barrel efficiently (hereafter referred to prior art 4); one in which are provided a lead screw for zooming in the first quadrant around the optical axis, a lead screw for focusing in the second quadrant, and a guide shaft for guiding lens frames to compose the lens barrel in small size (hereafter referred to prior art 5); and one in which an object side lens is retained in a upper housing, lens frames for zooming and focusing are driven by two lead screws respectively, bearings for the two lead screws and two guide shafts of the lens frames are provided in the upper housing, and CCD is attached to the lower housing (hereafter referred to prior art 6).
Further, as a camera module, there are known one which is downsized by locating a lead screw for autofocusing and a lead screw for zooming on one side of the case and making it possible to assemble lenses from one side of the lens barrel of the camera module (hereafter referred to prior art 7), and one in which switching between telephotographing and macro-photographing in pan-focus lenses is done by means of a cylindrical cam located in the vicinity of lens frames (hereafter referred to prior art 8).
However, the apparatus recited in patent literature 1 relates to a relatively large camera module for a video camera and consideration is not taken into for downsizing the camera module as is in the case of a camera module to be equipped to a portable terminal. The apparatus disclosed in patent literature 2 is a small sided camera module to be incorporated in a portable terminal, etc., but it is of mutual operation type and can not be applied to a camera module in which zooming and autofocusing are performed by means of a motor. Further, the structure disclosed in patent literature 3 teaches simply a method of fixing lenses and there is no description concerning the method of assembling the lenses, a lens moving mechanism including cam, motor, and gears composing a camera module.